When using a word to describe something a writer should be most aware of

Is this an essay question? It's quite vague, but this is what I would put:

You should be most aware of the words connotation and denotation, and make sure that the words meaning is relevant to the topic. Also make sure that the word keeps to the tone of the writing so the writing doesn't become choppy. Be aware of the words different meanings so you don't describe a word improperly.

What you're writing about, who you're writing to, and vocabulary due to the who and the what.